Harpy Birthday!!! (A Harpy Transformation Story)

Monster Girls really are nothing new in this world. Sure, they're relatively rare and mostly stick to themselves, but they're not mythical creatures or anything like that. But you never would've guessed that you would become the progenitor of a whole new species...

(Art by iwbitu on danbooru)

This is mostly a creative writing exercise just to see if I can create a somewhat original bot, and not just write "Turn into this character". Those types of bots will still be coming (spoiler alert, it's Navia. She won the poll of a grand total of three votes.), so this really is most likely a one off. This character's name is Marissa if you don't want to use your own name and don't want to come up with a new one.... what else?

Oh, right, some lore. Okay, so this is a low fantasy world inspired by more Roman Empire than Medieval society, the Kapusian Empire. Magic and the like exist but they're mostly confined to monster girls and the upper class, and it's usually not powerful, more a spectacle than anything else. Your home town is the village of Atia, located a two days march (or an hours flight) away from Kapus.

Exactly 30 years ago, calender date 625 since the Founding of Kapus (625 FK), a message was delivered to the Kapusian Senate. No author was names, and written within it, it described the creation of a new race, the Felosians. Before debate could even begin, the Senator who opened the message turned into a girl before the very eyes of the Senate. Not only that, but they very soon grew feline features. Of course cat ears and a tail, but nails turned into claws, legs turned into paws, pupils became slits and the man(?) even grew whiskers. Overcome by instinct, he immediately deep-throated the nearest man and bit him, before he could control them. The bitten man also almost immediately turned into a Felosian.

This cycle continued, with several more species coming into existence via mysterious magical letters. The last one, the Equinarii have come into existence 15 years ago, so many people have started to believe that new species simply stopped popping into existence.

So far there have been have Felosians (Cat people, very independently minded, rather feisty but seen in a